Regarding the antecedents of the present invention, some previous patents are known in which the methods of elaboration containing Venlafaxine HCl were developed.
In these patents, the cores are elaborated from the mixture of the active drug with microcrystalline cellulose, which is crushed and granulated utilizing hydroxypropilmethylcellulose dispersed in water as binding; such a dispersion may be prepared onsite in previous form. This wet mass is extruded, shaped into spheres, dried and purified (to select granulometries); the micro granules being obtained with the incorporated, and without coating, active drug, with the property of “immediate liberation”.
In these same patents, it is also claimed that the elaboration of cores are without the presence of hydroxypropilmethylcellulose, although this is utilized soon after and duly mixed with ethyl cellulose, in the after phase of coating application.
To get the “programmed liberation” properties, the micro granules are covered with a tissue, by the deposition of a mixture of ethyl cellulose and hydroxypropilmethylcellulose. This process is realized in a liquefied bed by aspersion of an ethyl cellulose solution and hydroxypropilmethylcellulose in a solvent consisting of a mixture of methylene chloride and methanol.